How Pet Food Contamination is Linked to Human Illness

There are numerous steps that take place to track and locate the source of a foodborne illness. The following information relating to connecting a pet food to human illness was provided by the Centers for Disease Control and Prevention (CDC).

I was curious as to how a pet food is tracked down ultimately connected to human illness. The following response to questions were provided by the CDC.

To find cases in an outbreak of Salmonella infections, public health laboratories serotype the Salmonella bacteria and perform a kind of “DNA fingerprinting” on Salmonella laboratory samples. Investigators determine whether the “DNA fingerprint” pattern of Salmonella bacteria from one patient is the same as that from other patients in the outbreak and from the contaminated food. Bacteria with the same “DNA fingerprint” are likely to come from the same source. Public health officials conduct intensive investigations, including interviews with ill people, to determine if people whose infecting bacteria match by “DNA fingerprinting” are part of a common source outbreak. The timeline for this process can be found here: http://www.cdc.gov/salmonella/reportingtimeline.html

What happened with this investigation is that the DNA fingerprint of the dog food that tested positive for Salmonella was uploaded to the database PulseNet and when human cases tested positive for Salmonella, their DNA fingerprints were also uploaded to PulseNet. PulseNet will easily identify the human cases that had the same DNA fingerprint as the dog food sample. Once human illnesses were identified, we conducted an outbreak investigation as described at http://www.cdc.gov/outbreaknet/investigations/

With the recent Diamond Pet Food recall, there were several human illnesses linked to the Salmonella DNA fingerprint Infantis prior to the pet food recall announcement. When the Michigan Department of Agriculture did random testing on pet food in early April, 2012 and when this first Diamond product tested positive for Salmonella, as explained by the CDC, DNA fingerprinting was done to determine the strain was Infantis. Michigan Department of Agriculture submitted the Infantis strain to PulseNet which alerted Officials to the previous human illnesses linked to the same strain. Those patients were interviewed again, and Officials learned of each patient’s exposure to a pet or a Diamond pet food.